JPS63263168A - Power steering gear - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to power assisted steering systems, and more particularly to an electrical control mechanism for supplying power to an electric auxiliary motor.

BACKGROUND OF THE INVENTION Many power-assisted steering systems are known that utilize hydraulic power, electric power, or a combination thereof. Examples of power-assisted steering systems are U.S. Pat. No. 3,983,935 and U.S. Pat.
No. 054.

In U.S. Pat. No. 3,983,935, an electric auxiliary motor is coupled to an input steering shaft and is energized in response to torque applied to the vehicle's steering wheel. When energized,
The electric motor provides rotational drive to the rack and pinion gear set, thereby assisting the driver in accomplishing steering movements.

U.S. Pat. No. 4,415,054 discloses a system in which an electric auxiliary motor having a rotatable armature is coupled to a nut of a ball-nut assembly.

The screw of the ball nut assembly is integrally constructed with the rack member of the rack and pinion gear set.

Rotation of the armature causes linear movement of the rack members.

The linear movement of the rack member causes steering movement of the steerable wheels of the vehicle, and the electric auxiliary motor is activated in response to torque applied by the driver to the steering wheel of the vehicle.

When activated, the electric auxiliary motor provides linear driving force to the rack member to assist the driver.

Conventional power auxiliary steering systems have typically used four solid state switch elements connected to the positive and negative terminals of the vehicle battery and the electric auxiliary motor in an "H" bridge arrangement. The solid state switch element is controlled by an electronic control unit (ECU) in response to electrically sensed steering force direction and sensed steering torque applied to the steering wheel of the vehicle. The ECU controls the direction of current through the electric auxiliary motor by controlling activation of paired solid state switch elements. The paired switching elements that are activated depend on the sensed direction of the applied steering torque. The ECU controls the magnitude of the current flowing through the electric auxiliary motor by pulse width modulating a signal that controls activation of at least one solid state switch element of the selected pair. The magnitude of the power assist is proportional to the motor current, which is controlled by controlling the impulse coefficient of the pulse width modulated activation signal.

Such steering systems have proven effective in achieving the desired function of providing adequate steering assistance under all vehicle operating conditions. However, it is desirable to reduce the cost of electrically assisted systems compared to known systems.

An important part of the cost of the system is (i) the component cost for the electronic components capable of carrying large amounts of current, including ancillary costs such as heat sinks, and (ii) the cost of properly controlling the electric auxiliary motor. dominated by the cost of the large number of electrical components required.

During high steering operations, such as parking on dry ground, the electric auxiliary motor requires as much as 65 amps of current to provide adequate assistance. Solid state switch elements capable of switching 65 amps are relatively expensive; a typical H-bridge type circuit requires four solid state switch elements.

Additionally, numerous other electrical components are required to control the H-bridge in response to the sensed steering torque and sensed steering force direction.

One example of a design disclosed in U.S. Pat. There is. The steering system disclosed in Patent No. 787 includes four mechanical switches connected in an rH type circuit configuration to an electric auxiliary motor, one terminal of the vehicle battery, and a drive circuit. A mechanical switch mechanism is provided. The drive circuit includes a single solid state switch element. When torque is applied to the vehicle's steering wheel, a pair of four switches mechanically engages the electric auxiliary motor to control the direction of power applied thereto. In this way, the mechanism does not require electrical elements to control the opening and closing of the pair of switching devices or to detect the direction of the electrical power; the magnitude of the current applied to the electric auxiliary motor is determined by the Controlled by pulse width modulation of a single solid state switch element.

Although the mechanism disclosed in U.S. Pat. No. 787, issued to Mr. Druchas, greatly reduces the number of electrical components required for an electric-assisted steering system, the solid-state switch element controlling the motor current still has a 65 amp opening/closing current. capability and it must be implemented at the frequency of the control signal which is pulse width modulated.

(Problem to be solved by the invention) It is more cost-effective than previous systems (i.e.
It is desirable to provide a power assisted steering system that (ii) uses a minimum of electrical components, tends to retain complete system control, and (ii) provides sufficient operating current to the electric auxiliary motor under all operating conditions. It will be done.

(Means for Solving the Problems) One embodiment of the present invention is a novel and novel method that selectively utilizes the output of a vehicle's alternator or the output of a vehicle battery to supply power for energizing an electric auxiliary motor. Provides an improved power auxiliary steering system that adjusts the output voltage of an alternator in response to detected vehicle operating parameters and provides variable power to drive an electric auxiliary motor in response to said operating parameters. A control mechanism is provided to do so. The output voltage of the alternator is controlled by adjusting the current flowing through the alternator's field coil. Throughout the auxiliary conditions, the field coil current, which is controlled mechanically, is
The current draw of the electric auxiliary motor, for example 65 amps, is significantly less, eg 4.25 amps, and can therefore be controlled more cost-effectively than known conventional systems.

(Function) A power-assisted steering wheel according to an embodiment of the present invention is operatively connectable with a steering linkage and provides a steering force in response to applied electric power. Equipped with equipment. The electrical signal generating device is operatively driveable by the engine and, when driven, produces a controllable electrical signal. A sensing device is provided for sensing operating parameters of the vehicle and generating electrical signals indicative of the sensed parameters. A switch device is connected to the generator and the power steering device, and in one position connects the generator to the power steering device. The switching device connects the generator to the power steering device according to the detected driving parameters of the vehicle.
Switch between two positions.

In one embodiment, the steering wheel of the vehicle is connected to an input shaft, the input shaft is connected via a torsion rod and a pinion gear, and a zero position detector connects the torsion rod to the input shaft and the pinion gear. and generates an electrical signal indicative of rotational excursion between the input shaft and pinion gear indicative of the amount of input torque applied. A vehicle speed detector is provided for detecting the speed of the vehicle and generating an electrical signal indicative thereof.

A mechanical switch mechanism is connected between the input shaft and the pinion gear, and is electrically connected to the electric auxiliary motor. The alternator is drivably connected to the vehicle engine,
When activated, it generates an electrical signal whose value is proportional to the current flowing through its field coil.

A first relay having a double pole single throw switch has a normally open switch connected to the vehicle battery and a mechanical switch mechanism. A second normally closed switch of the first relay is connected to the mechanical switch mechanism and to electrical ground. A second relay having a double pole double throw switch is connected to the output of the alternator and the vehicle battery and the mechanical switch mechanism via a current detector to selectively connect the output of the alternator to the battery or the mechanical switch mechanism. It has a first switch. A second switch of the second relay is connected to the field coil of the alternator, the electronic control unit, and the voltage regulator to selectively connect the field coil to the ECU or the voltage regulator. The power modulator is connected between the mechanical switch and earth, and the EC
Connected to U.

The ECU monitors the output current from the alternator, the applied steering wheel herb and vehicle speed, and controls the relays accordingly. If the quadratic torque is less than a predetermined value, the alternator is connected to the battery for charging. When the steering torque is above a predetermined value, the alternator is connected to the electric auxiliary motor to energize the electric auxiliary motor via actuation of the second relay. The output of the alternator is controlled by a control current through the alternator field coil.

If the output current of the alternator is less than a predetermined value, the battery is connected to the electric auxiliary motor via activation of the first relay, and the auxiliary power is controlled using a power modulator.

According to another embodiment of the invention, two alternators are driven from the vehicle engine. One alternator powers all of the vehicle's electrical loads except the electric auxiliary motor. A second alternator powers the electric auxiliary motor. The two alternators each have their own voltage regulation circuit. A voltage regulation circuit for an electric auxiliary motor alternator controls current through an associated field coil in response to at least one vehicle operating parameter.

Vehicle operating parameters include applied torque and vehicle speed.

(Example) Next, an example of the present invention will be described in detail with reference to the accompanying drawings.

A vehicle power auxiliary steering wheel fI110 is shown in FIG.
It includes a steering handle 12 mechanically coupled to a pinion gear 14 via an input shaft 16 and a torsion rod 28.
The pinion gear 14 engages a rack arranged on a steering member 18, which is connected in a known manner to the steerable wheels 20.22 of the vehicle. When the steering wheel 12 is rotated, the steering wheel 20.22 performs a steering movement.

An electric auxiliary motor 24 surrounds the steering member 18 and is drivingly connected thereto by a ball and nut drive flI (not shown). An electric auxiliary steering system having such an electric auxiliary motor and a ball-and-nut drive mechanism is disclosed in U.S. Pat. No. 4,415,054.

Mechanical switch mechanism 32 is coupled across torsion rod 28 to input shaft 16 and pinion gear 14 .

As shown in FIG. 2, switch v1ffi 32 includes four mechanically actuatable switches 34, 36, 38 and 40 connected in an "H" circuit configuration. Switches 34, 36, 38 and 40 separate the torsion rod 28,
The switch pair is mechanically coupled to activate the switch pair when the torsion rod is twisted.

The four switches are normally open when no torque is applied to the vehicle's steering wheel 12. These switches close in tandem when steering wheel torque is applied to the steering handle 12. Switch 34.40 closes when input torque is applied to the steering handle 12 in one direction, and switch 36 closes when input torque is applied to the steering handle 12 in the other direction.
．． 38 closes.

The junctions of switches 34 , 38 are connected to one side of the electric auxiliary motor 24 and the junctions of switches 36 , 40 are connected to the other side of the electric auxiliary motor 24 . Switch 38.
Junction 40 is connected to ground and switch 34 .
36 junctions can be connected to a source of electrical energy. Such a mechanical switch mechanism is disclosed in U.S. Pat.
No. 87 discloses this in detail.

A position detector 42 is connected to the input shaft 16 and the pinion gear 14 across the torsion rod 28 and provides an electrical signal having a value proportional to the relative rotation of the input shaft 16 and the pinion gear 14. together with the torsion rod 28 form a torque detector. The output signal from detector 42 is proportional to the amount of input torque applied to the vehicle's steering wheel.

The detector 42 is connected to an electronic control unit (E CU >44. The output from the speed detector 46 is also connected to the ECU 44.
is connected to. Speed detector 46 monitors the vehicle's road speed and generates an electrical signal indicative thereof.

An alternator 50 is provided which includes a rotatable field coil 52 and a "Y" shaped stator coil 54.
including. The field coil 52 can be driven in rotation by a vehicle engine 56 in a known manner via a belt. The output of stator coil 54 is rectified by diode network 58. The output of the diode network 60 is the output of the alternator 50.

Output 60 is a DC voltage whose value is proportional to the current flowing through field coil 52. The field coil 52 can be selectively connected to the voltage regulator 62 or the ECU 44 via one switch 63 of the double-pole double-throw relay R2 and the output amplifier 64.

Relay R2 is operatively connected to and controlled by ECU 44. Control of the alternator by the ECU 44 or the voltage regulator 62 will be described in detail later.

The vehicle battery 68 is connected to the switch 67 of the single-pole single-throw relay R1.
It can be selectively connected to the mechanical switch mechanism 32 via. Relay R1 is operatively connected to and controlled by ECU 44. The operation and control of relay R1 will be detailed later.

The second switch 68 of the double-pole double-throw relay R2 connects the output of the alternator 50, the battery 66, and the mechanical switch mechanism 3.
It is connected to the junction of two switches 34 and 36.

A switch 68 connects the output 60 of the alternator 50 to the battery 6.
6 or mechanical switch mechanism 32. Other electrical loads 69 such as lights, wipers, radio, etc. are connected to battery 66 in the conventional manner.

Power to operate ECU 44 is derived from battery 66. Ignition switch 70 connects ECU 44 and voltage regulator 62 to battery 66 when it is in the "run" position.

During operation, the ECU 44 determines whether power assistance is required for the input steering action based on (i>vehicle speed and applied steering torque; and (ii) if steering assistance is required. controls whether the battery or the alternator powers the mechanical switch mechanism 32;
ii) adjusting the output voltage of the alternator 50 in response to the detected vehicle speed and the detected steering torque applied to the vehicle steering wheel when the alternator is connected to the mechanical switch mechanism 32; and (i) connect the alternator to the battery for battery charging purposes when steering assistance is not required.

Current detector 71 is connected to output 60 of alternator 50. The current detector 71 can be of the inductive or resistive type, for example. Current detector 71 outputs an electrical signal 72 indicating the current output from alternator 50 to ECU 44 . The ECU 44 monitors the output signal from the current detector 71.

Referring to FIG. 2, the ECU 44 includes a non-linear network 73 connected to the output of the position sensor 42. The output signal from the position sensor 42 is detected when no input torque is applied to the steering wheel 12. For example, 4V.

It has voltage values of D and C. When a torque is applied to the steering wheel 12 in one direction or the other, the output signal from the position sensor 42 increases or decreases from its no-torque voltage value. A non-linear network 73 processes the output signal from the position detector 42 and outputs a non-linear signal having a waveform as schematically shown in FIG. 2, where the Y-axis is a DC voltage. , and the X-axis is the applied left and right hexagonal torque.

The output signal from the nonlinear network 73 is connected to an absolute voltage amplifier and bias circuit 74 such that the Y-axis value is O at the Y-axis intersection (e.g., the torque detector output transpose the Y-axis value of the output signal from the nonlinear circuit 11g73 (by subtracting the DC voltage from the signal)
Circuit 74 also takes the absolute value of the resulting bias shifted signal. After the transposition is done and the absolute value of the detector signal is taken, the resultant transfer characteristic (torque vs. output signal) is basically that if the torque input (X value) is equal to 0, then the output (Y value) is 0. It has a parabolic shape equal to .

The output signal from the vehicle speed detector 46 is operatively connected to a non-linear network 76 which outputs a control signal to the absolute voltage amplifier and bias circuit 4. The control signal from non-linear circuit 11176 controls the gain of circuit 74 and thus the shape of the parabolic transfer characteristic of circuits 73,74.

The gain is preferably an inverse function of vehicle speed such that the gain (and thus torque assistance) decreases as speed increases. Therefore, the output signal from circuit 74 is functionally dependent on both the applied hexagonal torque and vehicle speed.

The output from circuit 74 is connected to one terminal of switch 63 of relay R2. The other terminal of switch 63 is connected to the output of voltage regulator 62.

The voltage mW generator 62 is connected to the battery 6 via the ignition switch 70.
6 can be connected. The regulator includes a voltage reference leg 78 having a resistor 80 and a Zener diode 82 connected in series across the vehicle battery 66. The voltage at the resistor and zener junction is equal to the rated voltage of the zener; the voltage regulator 62 further includes a voltage sensing leg 84 having a resistor 86 connected in series across the vehicle battery 66. The resistor-to-resistor junction of the differential amplifier 90
connected to two inputs. The resistor-zener junction is connected to another input of differential amplifier 90. The output of differential amplifier 90 is the output of voltage regulator 62 and relay R
It is connected to the terminal of switch 63 of No. 2. Relay R2 connects field coil 52 of alternator 50 via power amplifier 64.
By connecting the output of voltage regulator 62 to
2 outputs enough current to charge the battery to a value controlled by the selected value of the Zener diode in voltage reference leg 78 of 2.

Relay R1 is controlled according to the output current from the alternator. Specifically, the output from the current detector 71 is transmitted to the comparator 9.
connected to one input of 2. The output signal from current detector 7e is a DC voltage whose value is proportional to the current output from alternator 50. The alternator 50 is the electric auxiliary motor 24
Or because it is always connected to the battery 66 and other loads, the alternator always outputs at least a minimum current level. Therefore, the output signal from the current detector 71 is
is always greater than some minimum value if the alternator 50 is operating properly.

Another input of comparator 92 is connected to a DC critical reference voltage circuit 94 that is less than the minimum DC level from detector 71 expected under all steady state operating conditions of alternator 50 . The output of comparator 92 is connected to and controls relay R1.

If the alternator output current is above a predetermined minimum value, ECU 44 generates an electrical signal to command relay R1 to open switch 67, thereby disconnecting the battery from the mechanical switch mechanism. . If the alternator fails, the drive belt breaks, or the vehicle engine stalls, the alternator output current will drop below a predetermined minimum value, an event detected by comparator 92. An electrical signal is then generated which closes switch 67 of relay R1 and connects the output of battery 66 to mechanical switch mechanism 32. In this manner, power for the electric auxiliary motor is supplied by the battery 66, providing power assistance.

Relay R2 is controlled depending on vehicle speed and applied torque group torque. Specifically, the output of absolute voltage amplifier and bias circuit 74 is connected to one input of comparator 95. The other input of the comparator 95 is a DC critical reference voltage circuit 96.
connected to. The output of comparator 95 is connected to and controls relay R2. As is known to those skilled in the art, as vehicle speed increases, it is desirable to reduce the amount of power assistance provided; as vehicle speed increases, the torque required to turn the vehicle steering wheel increases. The power assistance decreases as the vehicle speed increases, resulting in a satisfactory steering feel at all vehicle speeds.

The graph shown above circuit 74 shows multiple possible output signals from circuit 74 that are a function of both vehicle speed and applied steering speed. The Y-axis is voltage and the X-axis is applied squirrel torque.

Each parabola represents an auxiliary characteristic for a given vehicle speed. When the vehicle speed is relatively low, the slope of the torque curve is relatively steep. As the vehicle speed increases, the slope of the torque curve becomes gentler. For a given amount of steering torque applied, the resulting output voltage from circuit 74 decreases as vehicle speed increases. Therefore,
The amount of power assistance available for a given amount of feeder torque applied decreases as vehicle speed increases.

Preferably, power assistance is not applied until the applied squirrel torque exceeds a predetermined level.

The predetermined level depends on the vehicle speed 0 times FIIr7
The predetermined minimum output voltage from 4 represents a predetermined amount of torque family torque that varies as a function of vehicle speed. The threshold voltage circuit 96 outputs a DC voltage equal to a predetermined minimum torque value below which no power assistance is applied.

When the applied squirrel torque at a predetermined vehicle speed is equal to or exceeds a predetermined minimum value, comparator 95 outputs a control signal to relay R2, which outputs a control signal to relay R2 via power amplifier 64 to the absolute voltage amplifier and The states of switches 63 and 68 are changed to connect the output of bias circuit 74 to field coil 52 and the output 60 of alternator 50 to mechanical switch 1i 132. If the output signal from circuit 74 is less than the output of critical voltage circuit 96, comparator 95 outputs a second control signal to relay R2 to connect voltage regulator 62 to alternator 50 via power amplifier 64. The states of switches 63 and 68 are changed to connect the field coil of AC generator 50 and the output of alternator 50 to battery 66.

To better understand the operation of the present invention, consider that the driver of the vehicle initiates a steering motion by applying torque to the steering wheel 12 of the vehicle. Further assume that the value of the applied rudder torque is sufficiently low for the sensed vehicle speed that the output of circuit 74 is less than the critical value output by circuit 96 at the sensed vehicle speed. Under such conditions, the ECU 44 controls the relay R2 via the comparator 95 to reduce the output 6 of the alternator 50.
0 and the battery 66 is maintained. Voltage regulator 62 controls the output of the alternator to maintain its output voltage at the normal charging voltage value.

Once steering torque is applied to the vehicle steering wheel at a level sufficient to cause the output of circuit 74 to be equal to or greater than the value output by critical circuit 96, ECU 44
relay R2 is controlled to connect the output of alternator 50 to mechanical switch f1t32. E
CU 44 controls the output voltage 60 of alternator 50 as a function of sensed vehicle speed and sensed rudder torque through absolute voltage amplifier and bias circuit F4.

While the electric auxiliary motor is powered by the alternating current source $ta, the other electrical loads 69 of the vehicle are powered only by the battery 66. Once the steering operation is complete, that is, once the sensed steering torque has fallen to a sufficiently low value for the given vehicle speed, the ECU 44, via comparator 95, causes relay R2 to change its switch state and switch off the alternator. 5
0 output 60 is connected to the battery 66 and the voltage regulator 6
2 is connected to the field coil 52.

Referring to FIG. 3, another embodiment of the invention is shown. In Figure 3, the same reference numbers refer to Figures 1 and 2 above.
It represents an element having the same structure as that of the embodiment shown in the figure. Power steering system 10' includes all of the elements described above in connection with FIGS. 1 and 2, and includes a power modulator 97 connected between mechanical switch mechanism 32 and ground. 97 is connected to and controlled by the ECU 44.

A relay R3 is provided in place of the above-mentioned relay R1. Relay R3 is a double pole single throw relay and includes a normally open switch 67' as described above with respect to switch 7. Relay R3 further includes a normally closed switch 98 connected in parallel across power modulator 97, which in its closed state shorts out the power modulator, thereby causing mechanical switch device fl
One side of 132 is connected directly to ground to produce the connection configuration shown in FIG.

The control of relay R3 is as described above regarding the control of relay R1. The output of comparator 92 is connected to relay R3. If the current detected from the output 60 of the alternator 50 is greater than or equal to a predetermined value determined by the critical output voltage of the circuit 94, the state of the relay R3 is such that switch 67' is open and switch 98 is closed. The zeroth order circuit 96 which is the state
When a steering torque is applied that is greater than or equal to the critical output voltage of 0, the state of relay R2 switches such that output 60 of alternator 50 is connected to mechanical switch mechanism fl132. The terminal is connected to ground via switch 98 of relay R3.

If the sensed output current of alternator 50 is less than a predetermined amount determined by the critical output voltage of circuit 94, comparator 92 generates a control signal that switches the state of relay R3 to switch switch 67'. closed and open switch 98, in this state the positive terminal of battery 66 is connected to switch 67' at the junction of switches 34 and 36 of mechanical switch mechanism 32.
The junction of switches 38 and 40 of one mechanical switch mechanism 32 connected via 1 is connected to a power modulator 97, which is connected to ground. The power modulator 97 is E
Controlled by the CU 44'', motor current is controlled via the electric auxiliary motor 24 in accordance with the applied steering torque and the detected vehicle speed.

In particular, the absolute voltage amplifier and bias circuit 74 includes a pulse width modulation (PWM) generator 99 connected to a power modulator 97.
connected to. A PWM generator generates a modulated control signal with a constant frequency and variable impulse coefficient. The duty cycle is controlled in response to an output signal from circuit 74 that is proportional to the applied steering torque and sensed vehicle speed, as described above.

Power modulator 97 preferably includes a solid state switch element, such as a FET (field effect transistor), operatively connected between the junction of switches 38 and 40 of the mechanical switch mechanism and ground. This switching element can be activated into an ON or OFF state by a PWM generator 99.

The motor current is proportional to the impulse coefficient of the output signal from PWM generator 99.

Referring to FIG. 4, yet another embodiment of the present invention is schematically illustrated using a microcomputer-based system and software control to achieve the same features and advantages of the embodiments described above. In FIG. 4, like reference numerals designate elements of the same structure as in the embodiments described above, ECU 44'' includes an A/D converter, which (i) detects position indicative of applied steering torque; The torque signal from the device 42 and (ii
> a speed signal from the detector 46 indicating the vehicle speed; and (ii
"The AC current detection signal 72 from the J current detector 71 and (i
i) 4A/ receiving a signal indicating the output voltage of the alternator
The D converter is connected to the microcomputer 1 by the bus 104.
Connected to 02. The operational interaction of the A/D converter 100 and the microcomputer 102 is well known to those skilled in the art and will not be described in detail here; essentially, the microcomputer addresses the drop-in lines of the A/D converter. The A/D converter outputs a digital signal indicating the voltage level of the addressed drop line.

The latch/driver circuit 106 is the microcomputer 1
02 output and to relays R4 and R3. Relay R4 includes a single-pole double-throw switch 68'' connected in the same manner as described above in connection with switch 68, the microcomputer monitors the torque signal and the speed detector and switches between relay R2 accordingly. It controls relay R4 functionally similar to that described above. Additionally, the microcomputer monitors the alternator current sense signal and controls relay R3 functionally similar to that described above.

A power amplifier 64 is connected to another output of the microcomputer 102 to control the alternator output by controlling the current through the field coil 52. In this microcomputer embodiment, the ECU controls the alternator in both of its operating modes: (i) its charging mode and (ii) its motor drive mode, thereby providing a separate Not only is there no need for a voltage regulator, but there is also no need for a relay switch to connect the field coil to the voltage regulator or ECU separately.During charging mode, the microcomputer monitors the alternator's voltage sense wires. and a power amplifier 64 to control the output of the alternator to the proper charging level.
A control signal is output to the field coil 52 of the alternator via the AC generator. During the motor drive mode, the microcomputer outputs a control signal to the field coil so that the alternator outputs an appropriate amount of power to drive the electric auxiliary motor depending on the applied steering torque and the detected vehicle speed. do.

Further, a PWM generator 99 connected to a power modulator 9) is connected to the output of the microcomputer 102.

PWM generator 99 and power modulator 97 operate functionally as described above.

Referring to FIG. 5, there is shown a flowchart of the operational steps of the electrically assisted steering system according to the embodiment of the invention shown schematically in FIG. Operation of the system begins at step 200 when the ignition switch 70 is placed in the "run" position after starting the vehicle.

At step 202, the output of position sensor 42 is measured to determine the applied steering torque. The output signal from detector 42 that is retrieved is representative of torque. In step 204, ECU 44'' measures the output of speed detector 46 to determine vehicle speed. In step 206, ECU 44'' measures the alternator current. The output signal of the current detector 71 is measured in order to determine.

At step 208, a determination is made whether the applied steering torque is greater than a predetermined minimum value. If the determination in step 208 is negative, the program proceeds to step 212. In step 212, the output of the alternator 50 is connected to the battery door battery 66 by relay R4 for charging, and in step 214, the output of the alternator 50 is connected to the battery door battery 66 for charging. controls the current through the alternator's field coil 52 so that the alternator outputs at the appropriate charge level.The program then returns to step 202 and proceeds through the loop as described above. .

If the determination at step 208 is affirmative, indicating that power assistance is required to accomplish steering action, the program proceeds to step 216 where the alternator output is increased to a predetermined minimum value. A determination is made as to whether or not this is the case. If the determination at step 216 is negative, the program proceeds to step 218 where battery 66 is connected to mechanical switch mechanism 32 by switch 67' of relay R3. The switch 98 of relay R3 is opened and the program proceeds from step 218 to step 220 where the ECU'' controls the power modulator 97 via the PWM generator 99 according to the measured vehicle speed and the applied steering torque. do.

If the determination at step 216 is affirmative, the program proceeds to step 222 where the alternator 50 is connected to the mechanical switch mechanism 32 via switch 68'' of relay R4 and the battery The switch 98 is closed and the power modulator 97
is short-circuited, and the switch 67' is opened. Step 224
The output of the alternator 50 is then controlled by the ECU 44'' in response to the measured steering torque and the measured vehicle speed.The program returns from step 224 to step 202.

Heretofore, the present invention has provided that the electric auxiliary motor is supplied with alternating current whenever the output current of the alternator is above a predetermined minimum critical value and the applied steering torque is above a critical value that is a function of vehicle speed. An embodiment has been described in which all power is provided by a generator.

In another embodiment of the present invention, the ECU 44'' may be configured to output power from either an alternator or a battery, depending on the amount of auxiliary power needed as determined by the sensed steering torque and the sensed vehicle speed. selectively supplies power to the electric auxiliary motor. If the amount of auxiliary power required requires less than a predetermined value, e.g., 10 amps of motor current, the ECU 44'' connects the battery to a mechanical switch l! j13
Connect to 2.

For currents below 10 amps, the battery and power modulator 97
If the amount of auxiliary power required requires a motor current greater than a predetermined value, for example 10 amperes, the ECU 44' switches the output of the alternator to the mechanical switch mechanism 32. and switch 98 is closed. The zero order motor current is controlled by controlling the current through the field coil of the alternator, as described above.

The amount of current required to accomplish a steering operation can be calculated from the steering torque signal and the vehicle speed signal. ECU
44'' calculates the amount of current and controls the power source, i.e. battery or alternator, for the electric auxiliary motor according to said calculated value.

Referring to FIG. 6, another embodiment of the present invention is schematically illustrated, in which like reference numerals designate elements of the same construction as in the embodiments described above, a first alternator 250 is Provides power for the vehicle's electrical load 69. First alternator 2
The stator coil 254 of the first alternator 250 is connected to the vehicle battery 66 and the vehicle via the ignition switch 70 . It is electrically connected to another electrical load 69 . A voltage regulator 256 of a type known to those skilled in the art is electrically connected to the first alternator 250 via an ignition switch 70 and a field coil 252. Voltage regulator 256 controls the current through the field coil such that first alternator 250 provides sufficient power to load 69 and charges battery 66 .

The power auxiliary steering system 10'' includes an electric auxiliary motor 24.
a second alternator for supplying power to the alternator.

The stator coil 264 of the second alternator fi 260 includes a field coil 262 that is rotatably driveable mechanically by the vehicle engine 56 via a belt and a pulley. switch 34
．． It is electrically connected to the joint of 36.

A position detector 42'' is operatively connected across the torsion bar 28 and receives an electrical signal 26 indicative of applied steering torque.
Outputs 6. As shown graphically, the relationship between output voltage and applied steering torque exhibits a parabolic curve in one preferred embodiment. The output of detector 42'' is electrically connected to the input of gain control amplifier 268. The output of vehicle speed detector 46 is electrically connected to the gain control input of amplifier 268. Output signal 270 is electrically connected to field coil 262 of second alternator 260 .

Amplifier 268 biases the input signal 266 from detector 42~ such that a voltage of O volts is output when the applied steering torque is equal to zero. The speed signal from the vehicle's speed detector is utilized to control the gain of amplifier 268 such that the gain is an inverse function of the detected vehicle speed. In this way, power assistance decreases as vehicle speed increases. Each of the parabolas shown for the output 270 of amplifier 268 represents a different vehicle speed; as the vehicle speed increases, the parabola becomes more gradual.

The control system for the second alternator of FIG. 6 is a closed loop system. When steering torque is first applied, amplifier 268 outputs a DC voltage to field coil 268 of the second alternator. Alternator 260 outputs electrical energy to electric auxiliary motor 24 in a direction controlled by mechanical switch mechanism 32 . Electric auxiliary motor is steering member 1
8, the output signal 266 from the detector 42'' decreases because the torsion rod 28 does not twist.Detector signal 2
66 decreases, the output signal 270 from amplifier 268
decreases, thereby closing the system loop.

First alternator 250 and second alternator 260 are shown as separate components. The vehicle may be equipped with two separate alternators driven by two separate belt and pulley mechanisms, or with field coils 252, 262 rotatably mounted on a single drive shaft. Two alternators may be implemented within a single housing; a single drive shaft may be driven by a single belt and pulley mechanism, allowing independent control of the two alternators. Therefore, separate connection terminals for the two field coils are essential.

The invention has been described above based on preferred embodiments.

Modifications and changes may be made by those skilled in the art upon reading and understanding this specification.6 The present invention includes all such modifications and changes as long as they come within the scope of the appended claims or their equivalents. It is something.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a vehicle steering system based on the present invention, FIG. 2 is a schematic diagram of a control circuit of a vehicle steering system based on the present invention, and FIG. 3 is a schematic diagram of a vehicle steering system based on the present invention. FIG. 4 is a schematic diagram of another embodiment of the vehicle steering system according to the present invention; FIG. 5 is a flowchart showing the operational steps of the vehicle steering system according to the present invention; FIG. 1 is a schematic diagram of another embodiment of a vehicle steering system according to the invention; FIG. Reference numeral 10 in the figure: Power auxiliary steering device 12: Steering handle 46: Speed detector 14: Pinion gear 50: Alternator 16: Input shaft
52; Field coil 18: Steering member
54: Stator coil 20: Wheel 58
: Diode circuit 22: Wheel 60: Output 24: Dynamic auxiliary motor 62: Pressure regulator 28:
Torsion rod 63: Switch 32: Mechanical switch mechanism 66: Battery 34: Switch
6F: Switch 36: Switch 68:
Switch 38: Switch 69: Load 40 switch 71: Current detector 42: Position detector F2: Electrical signal 44: Electronic control unit (
ECU> 73: Non-linear circuit network 76: Non-linear circuit network ) 4: Bias circuit 78: Pressure reference leg
252: Field coil 80: Resistance 256:
Voltage regulator 82: Zener diode 260: Second
AC generator 84: Voltage detection leg 262: Field coil 86: Resistor 264: Stator coil 88
:Resistance 266:Electric signal 90:Differential amplifier 268:Amplifier 92:Comparator 2
70: Output signal 94: Critical reference voltage circuit 95: Comparator 96: Critical reference voltage circuit 9F: Power modulator 98: Switch 99: Pulse width modulation generator 100: A/D converter 102: Microcomputer 250: No. 1 AC generator (4 people included)

Claims (1)

[Claims] 1. A power steering device comprising: power steering means for providing steering force to a steering linkage in response to a supplied electrical signal; an electrical signal generating means operatively driveable by the engine to generate a steering torque; a detecting means for detecting steering torque applied by the driver; and a detecting means connected to the generating means and the power steering means. , 1st
switch means for connecting said generating means to said power steering means in a position of and for supplying said electrical signal from said generating means to said power steering means; and in a second position connecting said generating means to a battery; 2. A power steering system comprising: a power steering system, wherein the switch means switches between the first and second positions in response to detected steering torque. 2. The apparatus of claim 1 further comprising adjustment means for adjusting the electrical signal provided from said generating means to said power steering means in response to the sensed steering torque. 3. The generating means is an alternating current generator having a field coil and an output coil, and the adjusting means adjusts the generated electric signal by a control current applied to the field coil. 2. The device according to 2. 4. further comprising a second detection means for detecting the speed of the vehicle, and the adjusting means adjusting the electrical signal from the generating means in response to both the detected steering torque and the detected vehicle speed. 3. The device according to claim 2, characterized in that: 5. The apparatus according to claim 4, wherein said power steering means is an electric auxiliary motor. 6. A claim further comprising a second switch means connected between the power steering means and the generating means to switchably control the direction of the electric signal applied to the power steering means. The device according to item 1. 7. In power-assisted steering systems utilized in vehicles having a steering wheel mechanically connected to steerable wheels via a steering connection to assist the driver in accomplishing steering movements. , an alternating current generator that is drivingly connected to an engine of the vehicle and includes an output coil and a field coil; , an alternator of the type in which the output voltage from the output coil is directly correlated to the current flowing through the field coil, and an alternator connected to the sensing means and the field coil in response to a signal generated by the sensing means; an electronic control means for controlling the output voltage from the alternator; and an electronic control means connected to the steering connection means, for assisting the driver in steering by supplying steering force to the steering connection means when driven. an electric auxiliary motor connected to the output of the alternator and controlled by the electronic control means to direct the output of the alternator to the electric auxiliary motor or the vehicle battery in response to a signal generated by the detection means; A power auxiliary steering system comprising: switch means for freely switching connection; 8. The detection means is connected to the electronic control means and includes a torque detection means for generating an electric signal indicative of the applied steering torque, and a torque detection means for detecting the speed of the vehicle and generating an electric signal indicative thereof. 8. The system of claim 7, further comprising speed detection means for controlling the vehicle, said electronic control means controlling said switch means in response to both detected vehicle speed and detected torque. 9. further comprising current detection means connected to the output of the alternator and the electronic control means for generating an electrical signal indicative of the output current of the alternator, and the electronic control means is connected to the output of the alternator; The system is further connected to a battery and an electric auxiliary motor and is controlled by the electronic control means to monitor the current, and is capable of switching the battery to the electric auxiliary motor if the output current of the alternator is below a predetermined value. 8. A system as claimed in claim 7, including second switch means for connecting to. 10. In a steering device for turning steerable wheels of a vehicle by rotation of a steering handle of the vehicle, an input shaft connected to the steering handle and configured to rotate together with the steering wheel; A steering member having a pinion, a torsion member resiliently connecting the pinion and the input shaft, and a rack drivingly engaged by the pinion and connected to the steerable wheels of the vehicle. means for mechanically coupling a steerable wheel of a vehicle with a steering wheel, the rotational movement of the pinion gear driving the steering member in an axial direction, means in the form of causing the wheels of the steering wheel to swivel; twist detection means for generating an electrical signal of varying value as a function of input torque applied to the steering wheel; and an electrical signal for detecting and indicative of the speed of the vehicle. speed detecting means for generating a speed; and speed detecting means drivingly connected to at least one of the input shaft, the pinion gear, and the steering member and assisting the movement when activated, and the assisting force at that time is applied. an electric auxiliary motor having a configuration that directly correlates with the electric energy supplied to the vehicle; an alternator for outputting correlated electrical energy from the output coil; an alternator connected to the torsion detection means and the speed detection means and connectable to a field coil of the alternator; electronic control means for generating an electrical control signal to the field coil in response to a speed signal; and powering the electric auxiliary motor in a direction responsive to the direction of steering torque applied to the steering wheel of the vehicle. a first switch means for connecting the alternator, the first switch means and the vehicle battery and controlled by the electronic control means to connect the detected torque and the detected vehicle speed; a second switch means for selectively connecting the output of the alternator to the battery or the first switch means in accordance with the invention. 11. further comprising a third switch means connected to the battery and the first switch means and controlled by the electronic control means; further connected to the output of the alternator and the electronic control means; comprising current sensing means for generating an electrical signal indicative of the output current of the
11. The apparatus according to claim 10, wherein the electronic control means is configured to cause the third switch means to connect the battery to the first switch means when the output current of the alternator is below a predetermined value. . 12. Secondary drive means connected to the battery of the vehicle and for supplying secondary power to drive the electric auxiliary motor; connected to the output of the alternator and the electronic control means; current detection means for generating an electrical signal indicative of an output current; said secondary drive means and said first
and third switch means connected to the switch means and controlled by the electronic control means, wherein the electronic control means switches the third switch when the detected current of the alternator is below a predetermined value. means for connecting said secondary drive means to said first switch means and for controlling electrical power from said secondary drive means in response to sensed steering torque and sensed vehicle speed; 11. The device according to claim 10. 13. In a steering device that rotates steerable wheels by rotation of a steering handle of a vehicle, an input shaft connected to the steering handle and rotating together therewith, a pinion gear, and the input shaft are provided. a steering member having a torsion member resiliently coupled to the pinion gear and a rack drivingly engaged with the pinion gear and coupled to the steerable wheels of the vehicle; means for mechanically coupling a vehicle steering handle with a vehicle steerable wheel, the pivoting motion axially driving the steering member to cause the steerable wheel to pivot; twist detection means for generating an electrical signal that varies in value as a function of the amount of input torque applied to the handle; speed detection means for detecting and producing an electrical signal indicative of the speed of the vehicle; and said input. an electric motor drivingly connected to at least one of the shaft, the pinion gear, or the steering member, the electric motor being configured to assist the movement when activated, the assisting force being functionally related to the applied electrical energy; an auxiliary motor drivingly coupled to the vehicle engine and including a field coil and an output coil for outputting electrical energy from the output coil as a function of a current flowing through the field coil when driven; a generator; voltage regulating means operatively connectable to the alternator output coil and the alternator field coil for controlling the output voltage of the alternator to a predetermined charge level; a torsion detecting means, connected to the speed detecting means and connectable to a field coil of the alternator, and generating an electrical control signal to the field coil in response to the torque signal and the speed signal. electronic control means for connecting electrical power to the electric auxiliary motor in a direction responsive to the direction of steering torque applied to the steering wheel of the vehicle; and an output of the alternator. the coil, the first switch means, and the battery of the vehicle, and is controlled by the electronic control means to direct the output of the alternator to the battery or the first switch in response to the detected torque and the detected speed. a second switch means for selectively connecting to the field coil of the alternator, the voltage regulating means and the electronic control means; second switch means for selectively connecting to the alternator field coil; a third switch means for selectively connecting the field coil of the alternating current generator to the voltage adjustment means or the electronic control means in response to the third switch means. 14. Current detection means connected to the output coil of the alternator and the electronic control means for generating an electric signal indicating the output current of the alternator, and connected to the battery of the vehicle and the first switch means; A fourth switch means controlled by the electronic control means and configured to connect the battery to the first output means when the output current of the alternator is below a predetermined value. Item 1
3. The steering device described in 3. 15, further comprising a fifth switch means connected to the first switch means, and a power modulator connected to the fifth switch means and the battery of the vehicle and controlled by the electronic control means, the fifth switch means 15. The steering system of claim 14, wherein said power modulator is operatively connected to said first switch means when the output of the alternator is below said predetermined minimum value. 16. the electronic control means is connected to the power modulator;
16. The steering system of claim 15, including a pulse width modulator for controlling the current flowing through the electric auxiliary motor in response to applied steering torque and sensed vehicle speed.